Having sought expert advice on the approvals process for ‘good’ heritage design (as per the new standards RIS 4472 etc) as possibly applied to the bogie, it seems that:
- If the George bogie is the one fitted to the Claughtons (and then re-used on Patriots and Crewe-built Jubilees to February 1934 – i.e. 5552-6 and 5607-5654) then we have a chance to use that as a basis for approval. However, the preserved locos are 5593, 5596, 5690, 5699, all nicely outside the range we want. Despite that, the bogie being in service till the end of steam counts for something.
- We need to catalogue the applications, fleet numbers, axle-loads, dates of introduction, scrapping dates and service type.
- We need to demonstrate that the bogie to 16832 was indeed used on the Claughtons, and check for any available information on the re-use by the LMS – for example, side control springs
- It may be worth checking just what changes were made to the design for the later Jubilee bogie, it looks very similar
From this we can start on a justification.
Some areas will be subject to change anyway – it seems bonkers to spend money on the curved slides ‘radial guides’ as it means the front and back guides are different. Roller bearings mean bigger horn gaps, and square section side control springs are out, unless we want to spend lots more for a worse outcome. We need to review the pivot too, to check it will control roll. If necessary, alterations may be required there.
It seems we may have to do quite a bit of justification either way, but on the other hand a full stress analysis of the bogie is not a minor job.
For the bogie wheel, the news is less good. Probably we will have to fully meet the modern load case. Any relaxation will be minor, in which case we may as well go for compliance. Bolted or riveted tyres are out, double-snip tyres as per Bulleid are accepted at a push, otherwise Gibson rings. My judgement as ex BR’s former wheelsets man is that the latter is entirely justified. Gibson rings would be hard to fit to the bogie wheel, and the small diameter means the inner snip height is limited – not good.